Assigkob to



I (-No Model.)

A. W. SJDAVIS.

MEOHANIOAL TELEPHONE.

No. 833,285. Patented Dec. 29, 1885.

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ARTHUR VJ. S. DAVIS, OF LOW ELL, MASSACHUSETTS, ASSIGNOR TO FREDERICK TAYLOR, OF SAME PLACE.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 333,285, dated December 29,1885.

Serial No. 145,830. (No model.)

To all whom it may concern.-

Be it known that l, ARTHUR W. S. DAVIS, a citizen of the United States, residing at L0well,in the county of Middlesex and @0111- monwealth of Massachusetts, have invented a new and useful Improvement in Mechanical Telephones, of which the following is a specification.

My invention relates to mechanical telephones; and it consists in an improved construction of the same adapted to increase the volume of sound and the distinetness of articulation, and in the devices and combinations hereinafter described and claimed.

In the accompanying drawings, Figure 1 is an isometric View of a mechanical telephone constructed according to my invention; Fig. 2, acentral longittu'linal section of the same; Fig. 3, a front elevation of the diaphragm secured to the baseblock, the mouth-piece being removed; Fig. 4, a front elevation of the base-block detached; Fig. 5. a side elevation of such a telephone attached to a wall of a building or room, the wall being in crosssec tion and having a compound plug or soundinodifier (also in section) surrounding the transmitting wire where said wire passes through said wall; Fig. 6, a side elevation of such a telephone and its eondnctingwirc, said wire passing through a similar sound-modifier (shown in longitudinal section) supported upon posts or brackets.

The base-block or body A of the telephone is formed of a large number of small sticks, a, of wood, preferably maple, each of square or such othercross-section as will allow the sticks to be placed close together in a bundle without spaces between them, the grain of the wood running lengthwise of the sticks, and the sticks being glued together side by side without interstices. Such a bundle or block of sticks, made in a shape approximating its final shape, is then turned true or otherwise Wrought to a symmetrical form-1hr instance, that of a cylinder-as shown, and a hole, B, is bored through the center thereof, longi tudinally, just large enough to allow the transmitting-wire \V to pass through without touching.

I have found that the conducting-power of the telephone is greatly increased and the metallic sound commonly heard in acoustic or mechanical telephonesis greatly diminished by forming the body, as described, of pieces of wood thus united. insulated or wound copper wire. end of the body A is provided with a manysided (preferably octagonal) sound-chamber, G, concentric with said body, the bottom or deepest part of said chamber being flat and 6.

at right angles to the longitudinal axis ofsaid body. The. front end of the body A is covered from the chamber outward with a ring or strip. D, of lead or similar insonorous ma terial, which strip has a reduced thickness 6 for a slight distance outward from its inner edge. Over the mouth of the chamber 0 is laid a diaphragm, E, of skin or other porous flexible sheet material, which diaphragm is applied to the thin part of the lead strip'D,

passing into thebase-block. The diaphragm is then stretched by weight suspended from its at center while the diaphragm is held in a l1orizontal position, and while so stretched from the angles of the chamber to the center of the diaphragm is tacked in strai ht lines from angle to angle through the strip D without ad- 8 ditional stretching between the angles. By a,

thus attaching the diaphragm to the strip D and the block A its greatest tension is along the radial lines which pass to the angles of the chamber. to the quantity and quality of the tone, with the chamber and diaphragm shaped as above described than with a circular chamber and a circular diaphragm, and 1 also find that the rticulation is improved by the lines of 11111 equal tension in the diaphragm,and that these lines are best arranged radially, and that an advantage is gained by the tension lines even when a cylindrical sound-chamber is use" The diaphragm, after drying, is rubbed wit powdered rosin to fill the pores thereof, an then varnish ed with shellac to prevent its vi- The wire \V is preferably 5 The front The object of the strip D is to di- 7 I have obtained better results as bratory qualties being affected by the absorption of moisture from the atmosphere. The end of the transmitting-wire is passed through the center of the diaphragm and through one 5 or more washers, T, of leather and knotted. The knot K is made by looping the wire and winding the end of the wire around the same two or three times. Into the loop thus formed may be hooked the wire of anothertelephone, to if desired. The front end of the loop should project about half-way through the mouthpiece F.

The action of the telephone will be improved by placing powdered rosin between the wash- 'ersagid between the inner washer and the diaphragm and by filling the pores of the same with rosin. In front of the diaphragm (but not in contact therewith) against the strip D is placed a mouth-piece,F,preferably of wood, the same being a ring which has an opening which flares outwardly before and behind equally from the middle of the ring. The inner bevel of the ring makes about the same angle with the plane of the ring or strip of '25 lead D that the diaphragm makes with said plane. The angle which the bevels of the opening make with each other is about forty degrees, and the diameter of the opening in the mouth-piece, at the middle thereof, is .30 about one-third of the diameter of the diaphragm. The shape of the mouth-piece allows the sound-waves from any part of the diaphragm to go out through the mouth-piece without striking against the outer bevel of said mouth-piece, as shown by dotted lines in Fig. 2.

I have found that the clearness of articulation of the telephone is increased by carrying the transmitting-wire through a central lon- 40 gitudinal orifice, B, in a sound-modifier, A, compounded of a bundle of sticks shaped and united togetherjust as the sticks which form the base-block A are shaped and united wherever said wire passes through the wall of a room or building, and I also use such a compound plug or sound-modifier back of the telephone, as shown in Fig. 6, whenever it may be necessary to deaden the metallic or ringing sound thereof. In all cases the modifier should so besupported just out of contact with the transmitting-wire and the central orifice in said v modifier should be just large enough to allow of this. The base-block A is insulated from the wall or other object by which it is supported by blocks of rubber It, or by a ring of rubber or other similar elastic material, to pre-. vent the vibrations from passing into such object.

I claim as my invention- 1. A diaphragm for an acoustic telephone, consisting of a sheet of flexible porous material having its pores filled with rosin, as and for the purpose specified.

2. An acoustic telephone having a body or base-block formed'of strips or pieces of wood arranged with their grain parallel to the transmitting-wire and united to each other laterally, as and for the purpose specified.

3. The combination of a diaphragm and a series of leather washers placed in front of of sheet-lead or similar insonorous metal cov- I ering the front end of said base-block, around said chamber, and having a reduced-thickness for a slight distance outward from the inner edge of said strip, and the diaphragm secured, as herein described, over the thin part of said strip, as and for the purpose specified.

5. The combination, in an acoustic or mechanical telephone, of a diaphragm concaved on its front face and a mouth-piece placed in front ofsaid diaphragm, said mouth-piece having a circular orifice flaring outwardly from the middle thereof equally in both directions, said diaphragm forming the same angle with the plane of its attaching edges as the inner bevel of said mouth -piece forms with said plane, as and for the purpose specified.

ARTHUR W. s. DAVIS."

Witnesses:

ALBERT M. MOORE, HERBERT R. WHITE. 

